Each of the three national party leaders has a particular mission to accomplish and a disaster to avoid in this week's debates. But with little movement in the polls in the two weeks since the race began, all of them have a common task: to shake up the electorate and then convince voters to settle on their party before election day, May 2.<br/>Here is what each leader needs to accomplish, and what each should fear.

STEPHEN HARPER
MISSION: To convince 5 per cent of voters that it’s time for a majority Conservative government.
This is the Conservative Leader’s fourth leaders’ debate. Most polls show Mr. Harper well ahead, but still shy of the votes needed to form a majority government. To win the 5 per cent or so of voters who are either uncommitted or soft supporters of another party, he needs to appear calm, reasonable, moderate and statesmanlike. Warm would be nice, too, but with Mr. Harper that’s asking for the moon.
WHAT HE SHOULD FEAR: Losing his temper.
When annoyed, the Conservative Leader shows it, with a grim face and a taut, tense speaking style. He can’t allow any of the other leaders to get under his skin. An ill-tempered Stephen Harper could end any hope for a majority.(Sean Kilpatrick/Sean Kilpatrick/The Canadian Press)

MICHAEL IGNATIEFF
MISSION: To shake up the race.
The Liberal Leader has been running a solid campaign, but the Liberals are behind the Tories in the polls, and Mr. Ignatieff is far, far behind Mr. Harper when voters are asked which leader they prefer as prime minister. Mr. Ignatieff needs to present himself as prime ministerial while also, in his one-on-one with the Conservative Leader, shaking voter confidence that Mr. Harper can be trusted with a third mandate.
WHAT HE SHOULD FEAR: Getting rattled.
This is Mr. Ignatieff’s first leaders’ debate. He faces three veterans who will seek to trip him up on his campaign promises and his fitness to lead. They will exploit any stumble. Mr. Ignatieff must at all costs avoid being thrown on the defensive.(Fred Lum/Fred Lum/The Globe and Mail)

JACK LAYTON
MISSION: To stay in the game.
The Liberals believe the path to power lies in stealing votes from the NDP. The Conservatives hope to poach NDP seats in rural ridings (because of the party’s confused stance on the gun registry) and in the Vancouver area, where there are several NDP-Tory matchups. Mr. Layton must convince voters that his party is a valid option for anyone whose primary goal is to prevent another Conservative government.
WHAT HE SHOULD FEAR: Being pushed to the side.
Both Mr. Harper and Mr. Ignatieff want to turn this election into a referendum on which of the two should be prime minister. The greatest danger Mr. Layton faces is being rendered irrelevant in the debate.(CHRIS WATTIE/Chris Wattie/Reuters)

POSTSCRIPT: GILLES DUCEPPE
The Bloc Québécois Leader has nothing to gain from the English-language debate, since he has no support among English Quebeckers. In the French-language debate, he need merely remind Quebeckers that his party has successfully represented the province’s interests in Parliament for almost 20 years. He has little to lose and less to fear.(Graham Hughes/Graham Hughes/The Canadian Press)